How Thumbnails Get rendered

Thumbnails get rendered on the UI by displaying an image with the path defined in a field in Solr. By default that field is 'thumbnail_path_ss' defined here. Once the path is indexed into solr and object would need to be re-indexed for the thumbnail to change.

The path gets indexed into solr by the Indexer. The default indexers can be found here. Each indexer uses a ThumbnailPathServer to generate the string used in solr Sound here.

You can change the default behavior by creating your own ThumbnailPathService and Indexer that includes a line to point to you new ThumnbnailPathService

module MyNamespace
  class MyIndexer < Hyrax::WorkIndexer
    self.thumbnail_path_service = MyNamespace::MyThumbnailPathService
  end
end

You will then need your work to point at your new indexer

class MyWork
  self.indexer = MyNamespace::MyIndexer
end